1. Field of the Invention
This invention relates to cases for tape cassettes and in particular to a device for enclosing the head of a tape cassette to prevent dust and other artificial materials from coming in contact with the tape. The invention also embodies a means for preventing the reels from unwinding and storing the cassettes on a rack or case.
2. Description of the Prior Art
Tape cassettes as commonly used today are a case containing two reels holding magnetic tape. The case is closed on all sides except for an opening at one side which permits access to magnetic recording and playback heads. Usually the cassette housing has ventilation openings on both sides of the cassette housing in the region where the playback head and recording head meet the tape. Each cassette has two reels and these reels are rotated by drive shafts which engage protrusions on the spindle of the reel. The openings in the recording and playback head allow dust to enter and dust can affect the quality of recordings on the magnetic tape.
U.S. Pat. No. 3,310,178 to Wright and U.S. Pat. No. 3,696,935 to Dean both involve very similar devices used on regular magnetic tape reels. Both involve a flexible band which is placed around the circumference of the reel and engages both rims of the circular plates which form the sides of these reels. A locking device holds the flexible band in place on the reel. Both patents describe a hook attached to the flexible band which is used to hold the reels on a horizontal rod or similar structure. Both of these devices provide a means of protecting the tape from exposure to dust and also for easy storage of the device. However, neither of these devices is suitable for use with a tape cassette.
Devices for the storage of cassettes are also known. U.S. Pat. No. 3,746,180 to Spiroch et. al. discloses a plastic cover which engages the raised portions along the side of the playback or recording opening of a tape cassette. This cover extends beyond the ends of the cassette and the ends which extend beyond the cassette side are placed on the rim of a storage box. The cover also carries a label which identifies the contents of the cassette. This device does not prevent the reels from unrolling and requires specially designed boxes for storage of the cassettes.
U.S. Pat. No. 3,747,745 to Esashi et. al. describes a cassette cover involving a plate which covers the opening which receives the recording and playback heads. Two side members are attached to this plate by hinges and swing down to enclose the side of the cassette. The two folding members are cut out in the region around the playback head so that they hit flush with the cassette cover but do not cover the raised portion near the playback head openings. The hinged members are kept closed by fastening means which fit through the openings of the reels of the cassette where the cassette engages the drive mechanism of a cassette player or recorder. The state objective for this invention was to provide a means for flat stacking the cassettes without adding to the amount of space presented by the raised portion around the playback and recording head area. This device will not cover the openings on the side of the cassette that covers the playback and recording location and dust and other impurities can pass into the cassette and affect the quality of the recordings.
Two patents on cassette covers have issued to Ackeret, U.S. Pat. No. 3,994,550 and U.S. Pat. No. 3,994,551. U.S. Pat. No. 3,994,551 describes a cover which engages the raised open end of housing and had two cams which fit into the teeth of reels of the cassette and prevent the reels from unrolling. U.S. Pat. No. 3,994,551 describes a housing which encloses the entire cassette and has a spring in the bottom of the cassette for holding the cassette in position. A cam engaging the teeth of the cassette reels is used to prevent the reels from unwinding.